Archos 97 Xenon Malware Foxda_Compass

[xenonProblem]

I have an Archos 97 Xenon. After some time I have installed from Google Play a free App called "Stable Compass", which didn't require any permissions. After the installation I have found that this app has any possible permissions. I have tried to uninstall it without success, than I have tried to boot the device with original settings, this also didn't help to remove malware app. I have found the app in the File manager as /system/app/Foxda_Compass.apk and Foxda_Compass.odex. Both files are protected, have root rights and I cannot delete them. I have tried to find original Firmware on the Archos Website, but for this model (Archos 97 Xenon) there is no firmware on the website. I have tried to ADB (Android Debug Bridge) to remove malware files, but I can not do this because it seems, malware has blocked correct ADB-USB connection. (I have installed ADB-USB drivers (for Windows 7) accordingly instructions from the Archos website, but the Windows hardware manager shows me Archos driver with code 28 (not installed) and ADB doesn't see it).
What shall I do to get original clean system?